So once the patent expires it's then morally fine to claim the "inspiration" for a certain design?

Yes. The inventor who has invested a lot of time and money in R&D should have had more than enough opportunity to reap the benefits of that investment by then.

Legally, yes. You get to decide on the morality of it.

Legal means application of the law, and law should be derived from morality. If we think something legal is not moral, it should not be legal and we should strive to change the law.

We're going on a tangent. The idea is that whoever comes out first and patents "it" get some exclusive use. After that it becomes public so others can use and build upon it.

If Braun was still marketing those products they might have complained. Apple said that they're making less money because people are buying Samsung phones that use Apple's patented idea /look and feel. True or not that's another story.